The native Orc6 promoter and UASt regulatory sequences are fused upstream of a hybrid protein composed of the N-terminal 206 amino acids of Hsap\ORC6 fused to the C-terminal 52 amino acids of Orc6. The protein contains a K23E amino acid substitution, a variant identified in a patient with Meier-Gorlin syndrome. The coding sequence is tagged at the N-terminal end with GFP.